This invention relates to a simplified, economical process for the production and refinement of alcohols having two and three carbon atoms wherein: the molar water-to olefin ratio is kept very small at relatively low temperature; by-products form in low concentration and are mostly easy to separate from the alcohol; and the water required in the hydrating process consists mostly of vapor condensate which is recycled directly into the process together with by-products that are in solution.
The catalytic hydration of ethylene at temperatures of especially 270.degree.-290.degree.C and pressures of especially 60 to 80 atmospheres gauge, and of propylene at temperatures of especially 170.degree. to 240.degree.C and pressures of especially 25 to 40 atmospheres gauge has long been known and is applied on a large technical scale. The molar water ratios (water to olefin) are between 0.6 and 1.0 : 1 in the ethanol process and 0.4 to 1.0 : 1 in the isopropanol process. The preferred catalyst is phosphoric acid on various support materials such as bentonite, diatomaceous earth, aluminum silicates and the like.
Conducting the reaction under the above-stated conditions of the prior art causes the formation with a high percentage of process water and high energy costs, of by-products consisting essentially of ether, aldehydes, ketones, butanols, higher secondary and tertiary alchols and higher hydrocarbons. Since these by-products cannot be completely separated by extractive distillation from the corresponding alcohol, namely ethanol or isopropanol as the case may be, purification of the raw alcohol produced has to be performed both by extraction and by distillation at high energy costs and investment costs if the quality requirements are high. This is especially true for secondary and tertiary higher alcohols which cannot be completely separated from the desired products. On the other hand, even though there is a certain market for these higher alcohols, the recovery of the by-products is unprofitable on account of the high costs, so that they have to be discarded or burned. Thus, depending on the activity of the catalyst and the manner in which it is used, 5 to 8 percent of the olefin put in (ethylene or propylene) is reacted to by-products and thus is largely wasted.